Thread: New engine design

Originally Posted by Dougal

...how do you inject fuel at TDC on these engines? In a conventional engine the injector is mounted in the head and can spray straight into the combustion bowl in the cylinder. This one has no good place to mount an injector.

The CAD images of the piston heads looked like they have a small indentation on one side for the fuel to squirt through between the two as they come together.

Originally Posted by bob10

When I was apprentice at the RAN school at Quakers hill, Sydney, [ HMAS Nirimba] , 1964-1968, an officer by the name of Vagg, developed a steam engine for cars, and developed it to the stage he had a prototype ready. He started the development in England, at the engineering school there.If anyone wants to know more, just google "vagg steam engine", really interesting story. Bob

Mobi ??

Originally Posted by Dougal

The opposed pistons are old news. Their efficiency is good, but not better than current 4 stroke tdi's. Emissions rules however are something that 2 strokes just can't meet.

Making matters worse, how do you inject fuel at TDC on these engines? In a conventional engine the injector is mounted in the head and can spray straight into the combustion bowl in the cylinder. This one has no good place to mount an injector.

How about where he pointed out in the video, injectors position hasn't always been pointing down directly over the top. Design the pistons right and you will have a efficient combustion chamber in the piston crown.

Originally Posted by lambrover

How about where he pointed out in the video, injectors position hasn't always been pointing down directly over the top. Design the pistons right and you will have a efficient combustion chamber in the piston crown.

Yes you can squirt fuel in from there, but not as well controlled as squirting from top down in a convention engine. I think they'd have big problems meeting current emissions regs, not to mention future ones.

Originally Posted by Dougal

Yes you can squirt fuel in from there, but not as well controlled as squirting from top down in a convention engine. I think they'd have big problems meeting current emissions regs, not to mention future ones.

It is supposed to more fuel efficient. And from the video it says that thermally its cooler, so it is more efficient as it turns fuel into energy as opposed to heat so must be more efficient in design. I don't see how that they will struggle with emissions

Originally Posted by lambrover

It is supposed to more fuel efficient.

I'll believe that when they publish some BSFC numbers. Until then it's just marketing, likely trolling for investors.
Current production car diesels can produce 1kwh from around 190g of diesel at best point. I'd put money on them not beating those.

Originally Posted by lambrover

I don't see how that they will struggle with emissions

.

Do you realise just how tight modern emissions controls are? Any cold spots in combustion in the cylinder and it won't pass. If it doesn't pass it can't be sold in first world countries.
When you squirt fuel from one side of the cylinder, you've got too much heat (high NOx formation) near the jet and late combustion over the other side.

They could mount a ring of injectors around the cylinder, but the cost and complexity of that would ensure they never sell any engines.

Originally Posted by lambrover

I don't see how that they will struggle with emissions

All 2 stroke engines, whether opposed piston or not, struggle with emissions largely because the incoming fuel mixture has to scavenge the exhaust gasses as it comes in. Fuel injection may be able to assist here, but this factor will probably be the killer for road use.

The opposed piston design is used quite a lot for very large diesel engines in supertankers and large container ships.

See Wärtsilä-Sulzer RTA96-C - Wikipedia, the free encyclopedia

This is considered the most efficient diesel engine yet produced. (Burns bunker fuel)

Cheers,

Lionel

That Wartsila though isn't opposed piston. It's a conventional inline arrangement.

With a BSFC of 171g per kwh the Wartsila is indeed impressive. At the other end of the scale a 2 litre 4 cylinder VW TDi engine can acheive 196g/kwh.

For comparison most tdi engines can get down to around 210 g/kwh, even the 25 year old Isuzu 4BD1T's can do 215g.
A non turbo idi toyota 1HZ or Nissan TD42 takes 300g of diesel for each kwh.